In electronic circuits many important functions require the technique of electromagnetic induction and conversion. The most commonly used element is the coil set. For instance, R.O.C. patent No. M290607 discloses a transformer for electronic devices. It includes a winding seat, an iron core set and a holder. The winding seat has a winding zone. The iron core set is coupled with the winding seat. The holder covers a portion of the iron core set and is located between the iron core set and an electronic device. The transformer is positioned upright on the electronic device at a selected height.
These days design of electronic products increasingly focuses on thin and light. The internal space height is limited. Hence the height of electronic element inside the products also becomes one of important factors in the design of coil sets. R.O.C. patent No. I268520 also discloses a transformer which includes a plurality of winding seats and a plurality of iron cores coupled with the winding seats. Each winding seat has a primary coil zone, a secondary coil zone and a through hole. The winding seats are coupled together to form a housing space. The transformer is designed in a transverse manner, hence greatly reduces the height needed in installation. However, when it is installed inside an electronic product, the coil zone and circuit elements of the electronic product have no mask between them, thus electromagnetic interference (EMI) easily occurs. At present, the simplest technique adopted is to wind the coil set by an insulation tape to reduce the EMI between the coil set and electronic product. But such an approach provides limited barrier effect. Moreover, the insulation tape is relatively fragile and easily damaged during transportation and assembly process. Hence EMI still cannot be fully avoided as desired.
Therefore, an iron core set and a coil rack with desired height and improved electromagnetic characteristics without generating EMI are needed to meet requirements of thin and light products in the current trend.